Step 1 - Select a Climate Station and Project Name

This tool provides results based on 91 climate stations throughout California. Use the drop-down menu to choose the climate station that best represents your project site. Climate stations are also shown on the map to the right. Click on any station on the map to learn its name, years on record, 85th percentile design storm, and other information. You will be able to override the design storm on the following page.

ACTON ESCONDIDO FC261 ALTURAS ARROYO SECO ASH MTN AUBERRY 2 NW BEN LOMOND #4 BIEBER BIG BAR 4 E BIG BEAR LAKE BISHOP AP BLYTHE BORON CALEXICO 2 NE CAMPO CHESTER CHICO UNIV FARM COLUSA 2 SSW CORCORAN IRRIG DIST COVELO CRESCENT CITY 3 NNW DE SABLA DEATH VALLEY DONNER MEM SP DOWNIEVILLE EUREKA WFO WOODLEY IS FAIRFIELD FIVE POINTS 5 SSW FT ROSS GOLDSTONE ECHO #2 GRASS VALLEY #2 HAT CREEK HOLLISTER 2 KERN RIVER PH 3 LA CRESCENTA FC251 C LAGUNA BEACH LAKEPORT LEBEC LIVERMORE LODI LONE PINE COTTONWD PH LOS ANGELES INTL AP LUCIA WILLOW SPRINGS MADERA MERCED MODESTO 2 MONTEREY MTN PASS NAVARRO 1 NW NEEDLES AP NEW CUYAMA FIRE STN NILAND OCEANSIDE MARINA ORICK PRAIRIE CREEK PK ORLEANS PARKER PINNACLES NM PISMO BEACH PLACERVILLE POMONA/FAIRPLEX POWAY VALLEY RED BLUFF MUNI AP REDDING AP RIVERSIDE FIRE STN 3 SACRAMENTO 5 ESE SAINT HELENA SAN DIEGO WSO AP SAN FRANCISCO DWTN SAN GREGORIO 2 SE SAN JOSE SAN MIGUEL WOLF RCH SANTA BARBARA MUNI AP SANTA MARGARITA BOOST SANTA YNEZ SCOTIA SEBASTOPOL SHASTA DAM SIMI SANITATION PLT SONORA SONORA JUNCTION STANDISH HICKEY SP STONY GORGE RSVR SUNSET STATE BEACH SUSANVILLE 1 WNW TEHACHAPI AP TEMECULA THERMAL FS #39 TWENTYNINE PALMS VENTURA VICTORVILLE PUMP PT WASCO YREKA YUMA PROVING GROUND

If you would like to give your project a name add it to the box below.

Project name (optional)

Stormwater and Schools +

Step 2 - Input a saturated hydraulic conductivity

Enter your project site’s saturated hydraulic conductivity based on on-site field data.

If you don’t know the saturated hydraulic conductivity, check with your local regulator to see if it is acceptable to use estimates from the US Department of Agriculture Natural Resources Conservation Service (USDA NRCS). If it is, you can view the USDA NRCS hydrologic soil group on the map to the right. Click on the color covering your project location to get an estimate of the saturated hydraulic conductivity.

If you want more information on infiltration rates commonly affiliated with different soil hydrologic groups and soil textures expand the "Tables" section below.

Tables +

  inches per hour

Warning: Must be a number between 5 and 0.01

Step 3 - Input the impervious area

The CA Phase II NPDES permit requires that the project site be divided into discrete drainage management areas (DMAs). Runoff from each DMA must be managed using LID BMPs that meet specific sizing criteria specified in the permit. The tool assumes that the DMA consists of a 100% impervious catchment draining to a LID BMP. Input the size of the impervious catchment of the DMA of interest for your project.

You can use your own measured area or calculate an area using the measure tool below.

Measure Tool +

Acres Hectares Square Feet Square Meters

Warning: Not a Number Larger Than Zero